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    <title>Document</title>
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<body>
    <img src="images/s.gif" alt="">
    <div>上午好</div>
    <script>
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        var div = document.querySelector("div");
        var date = new Date();
        var hour = date.getHours();
        if (hour < 12) {
            img.src = "images/s.gif";
            div.innerHTML = "上午开始写代码";
        } else if (hour < 18) {
            img.src = "images/x.gif";
            div.innerHTML = "下午开始写代码";
        } else {
            img.src = "images/w.gif";
            div.innerHTML = "晚上开始写代码";
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